Elevated errors on Claude Sonnet 4.5

Incident Report for Claude

Postmortem

On January 21, 2026, from approximately 14:00 to 15:26 UTC, some users experienced increased error rates and slower response times when using Claude Sonnet 4.5 through our API. The issue was caused by insufficient compute capacity allocated to meet demand, and was resolved by our team scaling up additional serving resources. We apologise for the disruption and will implement monitoring improvements to detect capacity constraints earlier.

Posted Jan 21, 2026 - 15:58 UTC

Resolved

This incident has been resolved.
Posted Jan 21, 2026 - 15:32 UTC

Monitoring

A fix has been implemented and we are monitoring the results.
Posted Jan 21, 2026 - 15:28 UTC

Identified

The issue has been identified and a fix is being implemented.
Posted Jan 21, 2026 - 15:01 UTC

Investigating

We are currently investigating this issue.
Posted Jan 21, 2026 - 14:44 UTC
This incident affected: claude.ai, platform.claude.com (formerly console.anthropic.com), Claude API (api.anthropic.com), and Claude Code.